Residual carrier occurs when a modulated output contains a residual unmodulated carrier tone. A primary cause of residual carrier is that mixers and modulators, which perform a mathematical multiplication function that results in a frequency transition, will generally have some leakage from a radio signal (RF) path to the output. In other words, a modulator will generally have some fraction of the RF unmodulated carrier that bleeds through to the output. A secondary cause of residual carrier in a quadrature phase shift keying (QPSK) modulator is amplitude imbalance between the in-phase channel (I-channel) and quadrature data channel (Q-channel). Any imbalance in the I-channel or Q-channel may result in some fraction of the unmodulated carrier appearing on the modulator output. Residual carrier is undesirable because it can cause interference with other users when bandwidth is being shared. The transmission of residual carrier may also be a violation of the federal communications commission (FCC) regulations.